1. Field of the Invention
The present invention relates to electric motors and more particularly to electric motors having cooling apparatus.
2. Background Art
Product satisfaction is driven at a particular product price point by product safety, product reliability, and product longevity. This is particularly so in the field of paper shredders, where a shredder can be expected to endure excessive or rough wear regardless of the heartiness of the shredder product specifications. Such excessive or rough wear can, over time, degrade the reliability and longevity of the shredder product, causing the user to become dissatisfied with the product. In some cases, repeated stresses on the moving parts of the shredder may cause part failure, leading to the expense of product repair or replacement, a further decrease in satisfaction, or even loss of goodwill for the respective purchaser in the paper shredder brand. Even marginally stressful moments of operation may, in the aggregate, take their toll on the operating machinery of the shredder.
One shredder part which can be vulnerable to mechanical and thermal stresses is the shredder electric motor, which can arise from, for example, frequent starting; overloading; jamming; prolonged, unloaded operation; and continuous, beyond-rating use. Unnecessary electrical usage also is undesirable. Over time, the cumulative stresses faced by a shredder motor may lead to premature failure, or to poor performance. A common thread with these stressors is the heating effects of motor current (I2R losses). Many sophisticated electronic controllers have been devised to reduce the effects of I2R losses upon motors. Complex mechanical cooling systems have been advanced for large motors, as well. However, in the sphere of fractional-horsepower electric motors, as used in light- to medium-duty paper shredders and industrial equipment, sophisticated electronic controllers and complex mechanical coolers can add prohibitive premiums to the motor cost, and to the cost to purchasers, reducing a manufacturer's market share. An inexpensive cooling apparatus for motors is needed.